1. Technical Field
The disclosure contained herein generally relates to multifunctional structures and methods of manufacturing multi-ply, multifunctional structures. In particular, the multifunctional structures of the disclosure function as both electronic devices and load-bearing elements.
2. Description of Related Art
Designs for vehicle and antenna systems aspire to a union of form and function: antennas that perform both structural and sensing roles. Such integrated technology could revolutionize intelligence, surveillance and reconnaissance equipment, enabling multiband, multimode detection for air, land and sea vehicles. Most current electronic antenna systems, however, are suboptimal and are often precluded from installation on smaller vehicles and protective gear due to the large size and weight of the required antennas.
Recent advances in materials and electronics as well as new design philosophies have resulted in a number of innovations. Antenna systems, for example, have been incorporated with the surfaces of load-bearing structures which may become elements of vehicles or protective equipment thereby resulting in unique multifunctional structures. Examples of such are the load-bearing antenna systems which are embedded in a vehicle structure. Incorporating or embedding the antenna into a surface of the vehicle structure helps to decrease the large space and weight burden typical of similar free-standing antennas.
This technology must be robust enough, however, to withstand a lifetime of harsh environmental conditions and a lifetime of flexure and material stresses. Moreover, the algorithms used to design antennas must be matured to guide the electronic elements over a curved surface. Thus, the design and manufacture of electronic devices that will be integrated with curved surfaces is both time consuming and expensive. For example, the electronic devices must be fabricated on substrates with known and consistent dielectric properties so that they function as expected and desired, in addition, conventional electronic fabrication techniques involve vacuum deposition, plating, etching and lamination which require the substrate material to be able to withstand high temperatures and/or chemical solutions; environments which may not be suitable for structural materials. Hence, the number of high performance electronic substrates currently available for use in multifunctional structures is limited.
The manufacture of these multifunctional structures has incorporated conventional electronic substrate materials either “as is” or with only slight modifications. Hence, these load-bearing antenna structures are not completely optimized, as the structural materials frequently do not have the required electronic properties, and the electronics are not fully integrated with the structure. Further, conventional electronic substrates typically do not exhibit the required mechanical properties such that they could tolerate significant in-service mechanical loads. Additionally, in order to make a useful, multifunctional structure which combines both electrical and mechanical properties, it is desirable to have the electronics conform to the shape of the structure. Conventional electronics manufacturing processes are limited in their ability to manufacture shape-conformal electronics.
Thus, the prior art approaches are able to fabricate structures and electronics using techniques and substrate materials which are industry limited. For example, a load-bearing wing structure is fabricated using techniques and materials which are standard for the aerospace composite industry. An electronic, device to be included on a wing structure is fabricated using materials standard for the electronics industry. As such, the electronic device would be formed on a substrate such as Kapton® or FR4 laminate and packaged in an enclosure (electronics box) to be placed somewhere inside the airplane or embedded in the wing composite material. Because the electronics are formed on a substrate which is not load-bearing, the embedded electronics will represent a mechanical defect for the wing. Thus, the previous approaches to fabrication of multifunctional devices either (1) embed the electronic element(s) directly onto the surface of the aircraft wing effectively creating a “hole” in the load-bearing structure or (2) deposit the electronic element(s) onto a ply of curable resin or other composite or laminate which is not load-bearing and which has been placed over the surface of the aircraft wing. The design of the aircraft wing and of the electronics may be easier using this conventional approach, but the performance of each component is compromised when the two are integrated (meshed together).
More innovative methods of incorporating electronic functions into vehicles, protective and military equipment are needed to make the aforementioned structures more efficient in meeting varied functional requirements simultaneously. Accordingly, there is a need for multifunctional structures and methods that enable fabrication of electronic elements directly on arbitrarily-shaped load-bearing materials while providing increased performance and functionality in the resulting multifunctional structures.